1. Field of the Invention
This invention relates to a lens barrel and an optical apparatus using the same, and more particularly to a lens barrel which contains therein a so-called front-lens-fixed type zoom lens in which a first lens group located nearest to an object side is fixed when shooting is performed or a so-called mono-focal-length lens or the like, the lens barrel being arranged to be in a compact size as a whole when shooting is not performed and to be highly suited, for example, for a video camera excelling in portability.
2. Description of the Related Art
Optical apparatuses such as video cameras have heretofore been arranged to use various front-lens-fixed type zoom lenses. In each of the zoom lenses, the first lens group located nearest to the object side is stationary in carrying out, for example, zooming and focusing actions when shooting is performed. A lens barrel having the front-lens-fixed type zoom lens contained therein has generally been arranged to have a first holding frame which holds the first lens group fixedly attached to a fixed member (a fixed tube). Therefore, the total length of the lens barrel remains unvarying both when shooting is performed and when shooting is not performed.
FIG. 1 is a sectional view showing the essential parts of the conventional front-lens-fixed type lens barrel. Referring to FIG. 1, a fixed member 1 has an image sensor which is not shown. A third holding frame 2 is arranged to hold an afocal lens L3 (a third lens group) and is secured to the fixed member 1. A fourth holding frame 3 is arranged to hold a relay lens L4 and to be movable in the direction of an optical axis while being guided by bars 4 and 5 which are fixed by the fixed member 1 and the third holding frame 2. The fourth holding frame 3 is thus arranged to be movable along the optical axis by a driving force of a driving motor 6 through a feed screw. A first holding frame 7 is arranged to hold a first lens group L1 and is secured to the fixed member 1 by means of a screw 8.
A second holding frame 9 is arranged to hold a second lens group L2 and is movable in the direction of the optical axis while being guiding by bars 10 and 11 which are fixed between the first holding frame 7 and the fixed member 1. The second holding frame 9 is thus arranged to be movable along the optical axis by the driving force of a driving motor 12 through a feed screw.
In the lens barrel having the front-lens-fixed type zoom lens contained therein as shown in FIG. 1, the first holding frame 7 is secured to the fixed member 1. Therefore, the total length of the lens barrel remains unvarying both when shooting is performed and when shooting is not performed, and even when shooting is not performed, the first lens group L1 is arranged to protrude toward the object side.
Camera-integrated type video cameras of the kind having liquid crystal monitors which have recently begun to appear in the market are arranged to have the whole camera length shortened in the direction of the optical axis of the photo-taking lens. Use of a photo-taking lens having a lens barrel extending long in the direction of the optical axis for a video camera of that kind poses a problem as the photo-taking lens is alone left protruding in the direction of the optical axis even when shooting is not performed, thereby degrading the portability of the video camera.